This is a longitudinal study of the natural history and intervention outcomes of patients infected with Campylobacter pyloridis (C.p.). The long term objective is the understanding of the possible etiologic role of C.p. in chronic gastritis. In 1988 we will have completed in New Orleans a randomized trial of bismuth subsalicylate vs placebo in chronic active gastritis. This will provide approximately 65 patients positive for Campylabactor (C+) and positive for gastritis (G+). Approximately 15 of these patients will represent failures or recurrances after bismuth therapy. There will also be approximately 35 C- G- patients, representing success of treatment. All patients will be followed up to 2 1/2 years; endoscopy, biopsy, Gram and Warthin Starry stains, cultures and Elisa tests for serum antibody will be performed every 6 months. Forty-three C+ G+ patients will be treated with bismuth subsalicylate and amoxicillin to test if the combined treatment will reduce the rate of relapses. Additionally 43 C+ G+ patients will be treated with sucralfate to test the hypothesis that cytoprotection alone may cure gastritis and clean C.p. from the gastric mucosa. All patients will be asked to respond to an epidemiologic questionnaire directed at pre- infection and pre-relapse events. The spouses of all patients will be asked to give blood for Elisa tests to address the hypothesis of oral transmission. Additionally the prevalance of gastritis in subjects from the Colombian Andes rural area of Narino will be studied to correlate C.p. presence with histology and other parameters.